Studies on the reaction catalyzed by dextran sucrase are being continued. Work is in progress in an effort to identify amino acids that are involved with the catalytic activity of the enzyme. This work is developing along two lines; namely the utilization of general protein modifying reagents in order to gain insight into the characteristics of these functional groups, and the utilization of potential active site directed inhibitors, that have the potential to alkylate the enzyme. Studies on the subunit structure of the enzyme are also being continued and will deal with issues related to the activity of subunits and the location of active sites on them. This work is also focusing on the association-dissociation process, and the chemical and physical characteristics of it. Variations in substrate structure are being examined by utilizing alpha fluoro derivatives of various sugars such as galactose, mannose, and 6-deoxyglucose. Additional studies are being carried out on a glucosylated form of the enzyme which is formed during a pulse with sucrose. The nature and significance of this derivative will be explored.